tamerlan visited a year ago. their father still lives there. and a youtube video uncovered exclusively by cnn may hold some clues as to a motive. nick paton walsh joins us now from dagestan to explain what is in this youtube clip. >> absolutely. shortly after his return from russia to the united states, tamerlan tsarnaev posted on his youtube channel a link to a video of an extremist who was killed not far from where i'm standing by russian special forces. just last december. is there a connection between this gun fight involving militant and police in dagestan, and one of the boston bombers? the you if tube page of deceased brother tamerlan tsarnaev suggests there might be. he put up a link to a video titled abu dujana. the video was removed but cnn has now found it, and it shows this man. abu dujana is the name used by an islamist militant. gadzhimurad dolgatov. russian special forces hit the hideout last december. an armored car brought in to kill as many as six militants inside, including doll go atf. the grisly aftermath showing their heav